Although similar terms in other languages have described an event marking large scale migration of a specific population from a place of origin, such as the biblical account of Israelites fleeing from Assyrian conquest (circa 740 BCE), in English, the term refugee derives from the root word refuge, from Old French refuge, meaning "hiding place". It refers to "shelter or protection from danger or distress", from Latin fugere, "to flee", and refugium, "a taking refuge, place to flee back to". In Western history, the term was first applied to French Huguenots, after the Edict of Fontainebleau (1540), who again migrated from France after the Edict of Nantes revocation (1685). The word meant "one seeking asylum", until around 1914, when it evolved to mean "one fleeing home", applied in this instance to civilians in Flanders heading west to escape fighting in World War I.

The first modern definition of international refugee status came about under the League of Nations in 1921 from the Commission for Refugees. Following World War II, and in response to the large numbers of people fleeing Eastern Europe, the UN 1951 Refugee Convention adopted (in Article 1.A.2) the following definition of "refugee" to apply to any person who:

"owing to well-founded fear of being persecuted for reasons of race, religion, nationality, membership of a particular social group or political opinion, is outside the country of his nationality and is unable or, owing to such fear, is unwilling to avail himself of the protection of that country; or who, not having a nationality and being outside the country of his former habitual residence as a result of such events, is unable or, owing to such fear, is unwilling to return to it."

In 1967, this legal concept was expanded by the UN Protocol Relating to the Status of Refugees.

The Convention Governing the Specific Aspects of Refugee Problems in Africa expanded the 1951 definition, which the Organization of African Unity adopted in 1969:

"Every person who, owing to external aggression, occupation, foreign domination or events seriously disturbing public order in either part or the whole of his country of origin or nationality, is compelled to leave his place of habitual residence in order to seek refuge in another place outside his country of origin or nationality."

The 1984 regional, non-binding Latin-American Cartagena Declaration on Refugees includes:

"persons who have fled their country because their lives, safety or freedom have been threatened by generalized violence, foreign aggression, internal conflicts, massive violation of human rights or other circumstances which have seriously disturbed public order."

As of 2011, the UNHCR itself, in addition to the 1951 definition, recognizes persons as refugees:

"who are outside their country of nationality or habitual residence and unable to return there owing to serious and indiscriminate threats to life, physical integrity or freedom resulting from generalized violence or events seriously disturbing public order."

European Union's minimum standards definition of refugee, underlined by Art. 2 (c) of Directive No. 2004/83/EC, essentially reproduces the narrow definition of refugee offered by the UN 1951 Convention; nevertheless, by virtue of articles 2 (e) and 15 of the same Directive, persons who have fled a war-caused generalized violence are, at certain conditions, eligible for a complementary form of protection, called subsidiary protection. The same form of protection is foreseen for displaced people who, without being refugees, are nevertheless exposed, if returned to their countries of origin, to death penalty, torture or other inhuman or degrading treatments.

The idea that a person who sought sanctuary in a holy place could not be harmed without inviting divine retribution was familiar to the ancient Greeks and ancient Egyptians. However, the right to seek asylum in a church or other holy place was first codified in law by King Æthelberht of Kent in about AD 600. Similar laws were implemented throughout Europe in the Middle Ages. The related concept of political exile also has a long history: Ovid was sent to Tomis; Voltaire was sent to England. By the 1648 Peace of Westphalia, nations recognized each other's sovereignty. However, it was not until the advent of romantic nationalism in late 18th-century Europe that nationalism gained sufficient prevalence for the phrase country of nationality to become practically meaningful, and for border crossing to require that people provide identification.

The term "refugee" sometime applies to people who might fit the definition outlined by the 1951 Convention, were it applied retroactively. There are many candidates. For example, after the Edict of Fontainebleau in 1685 outlawed Protestantism in France, hundreds of thousands of Huguenots fled to England, the Netherlands, Switzerland, South Africa, Germany and Prussia. The repeated waves of pogroms that swept Eastern Europe in the 19th and early 20th centuries prompted mass Jewish emigration (more than 2 million Russian Jews emigrated in the period 1881–1920). Beginning in the 19th century, Muslim people emigrated to Turkey from Europe. The Balkan Wars of 1912–1913 caused 800,000 people to leave their homes. Various groups of people were officially designated refugees beginning in World War I.

League of Nations

The first international co-ordination of refugee affairs came with the creation by the League of Nations in 1921 of the High Commission for Refugees and the appointment of Fridtjof Nansen as its head. Nansen and the Commission were charged with assisting the approximately 1,500,000 people who fled the Russian Revolution of 1917 and the subsequent civil war (1917–1921), p. 1. most of them aristocrats fleeing the Communist government. It is estimated that about 800,000 Russian refugees became stateless when Lenin revoked citizenship for all Russian expatriates in 1921.

In 1923, the mandate of the Commission was expanded to include the more than one million Armenians who left Turkish Asia Minor in 1915 and 1923 due to a series of events now known as the Armenian Genocide. Over the next several years, the mandate was expanded further to cover Assyrians and Turkish refugees. In all of these cases, a refugee was defined as a person in a group for which the League of Nations had approved a mandate, as opposed to a person to whom a general definition applied.

The 1923 population exchange between Greece and Turkey involved about two million people (around 1.5 million Anatolian Greeks and 500,000 Muslims in Greece) most of whom were forcibly repatriated and denaturalized from homelands of centuries or millennia (and guaranteed the nationality of the destination country) by a treaty promoted and overseen by the international community as part of the Treaty of Lausanne.

The U.S. Congress passed the Emergency Quota Act in 1921, followed by the Immigration Act of 1924. The Immigration Act of 1924 was aimed at further restricting the Southern and Eastern Europeans, especially Jews, Italians and Slavs, who had begun to enter the country in large numbers beginning in the 1890s. Most European refugees (principally Jews and Slavs) fleeing the Nazis and the Soviet Union were barred from going to the United States until after World War II.

In 1930, the Nansen International Office for Refugees (Nansen Office) was established as a successor agency to the Commission. Its most notable achievement was the Nansen passport, a refugee travel document, for which it was awarded the 1938 Nobel Peace Prize. The Nansen Office was plagued by problems of financing, an increase in refugee numbers, and a lack of co-operation from some member states, which led to mixed success overall.

However, the Nansen Office managed to lead fourteen nations to ratify the 1933 Refugee Convention, an early, and relatively modest, attempt at a human rights charter, and in general assisted around one million refugees worldwide.

1933 (rise of Nazism) to 1944

The rise of Nazism led to such a very large increase in the number of refugees from Germany that in 1933 the League created a high commission for refugees coming from Germany. Besides other measures by the Nazis which created fear and flight, Jews were stripped of German citizenship by the Reich Citizenship Law of 1935.